1. Field of the Invention
This invention pertains to intraoperative monitoring methods and devices, and more particularly to intraoperative monitoring devices and methods for monitoring temperature-induced changes to tissue with high resolution digital X-ray imaging and inducing the changes to the tissue.
2. Discussion of Related Art
Various types of thermotherapy have been considered, and/or applied to the treatment of cancers. Laser interstitial thermotherapy (LITT) has received attention as a surgical procedure for the treatment of cancer tumors, and particularly with respect to liver, head, neck and breast cancer.
Laser interstitial thermotherapy is a surgical procedure for the treatment of cancer tumors in which near infra-red laser energy is delivered to the tumor site inside the body through a flexible fiber-optic probe. Some fiber optic probes in use terminate with a light diffusing tip. The infra-red laser radiation is absorbed by the tumor cells, which results in a temperature increase and subsequent cell death of the tumor cells. The temperature distribution around the light-diffusing tip, and thus the extent of cell-death, is a function of the laser parameters, treatment time, tumor size, and shape, fiber optic tip geometry, optical properties of the tumor, and blood perfusion rates in both compressed and uncompressed treatment sites.
The treatment parameters (e.g., wavelength, power, duration, tip geometry, and tip location and orientation) must be selected so as to minimize collateral damage to healthy tissue surrounding the tumor, yet still must ensure reliable total tumor destruction. Because of tissue inhomogeneities, and inter-patient variability of the physical and biological properties of tumors, intraoperative monitoring of the treatment effect is highly desirable. Currently, intraoperative monitoring of LITT is conducted with magnetic resonance imaging (MRT) or three-dimensional ultra-sound, or by measuring the temperature at discrete locations in-situ with thermocouples or thermo-sensing fluorescent probes.
Intraoperative monitoring with MRI has numerous disadvantages which include being expensive and not being able to be used with metal protected light guides which are currently used for the LITT probe. Three-dimensional ultra-sound imaging techniques are currently at an experimental stage and have not been sufficiently developed. In situ thermo-couples or fluorescence-based temperature probes only provide temperatures at a relatively small number of points throughout the tissue being monitored. Currently, only fluorescence-based temperature probes are approved by the FDA for clinical use.